Research Article
Determination of Aerodynamic Characteristics for a Vehicle with Wraparound Arc Fins by DATCOM and Fin Segment Approximation Method
Issue:
Volume 11, Issue 2, December 2025
Pages:
23-28
Received:
12 August 2025
Accepted:
9 September 2025
Published:
10 October 2025
Abstract: In evaluating the system performance, such as vehicle stability, controllability, guidance accuracy, etc., the analysis of aerodynamic characteristics of the vehicle is a priority. In vehicle preliminary design it is necessary to quickly and economically estimate the aerodynamic characteristics of a wide variety of configuration designs. Since the aerodynamic performance are so dependent upon the subsystems utilized, such as payload size, propulsion system selection and launch mechanism, the designer must be capable of predicting a wide variety of configurations accurately. The fundamental purpose of DATCOM is to provide an aerodynamic design tool which has the predictive accuracy suitable for preliminary design, and the capability for the user to easily substitute methods to fit specific applications. However, DATCOM tool has not yet been able to interpret WAF (wraparound arc fin). In this paper, a methodology for determining aerodynamic characteristics of a vehicle with a WAF is presented based on the DATCOM method and the segment approximation of the WAF. First, based on the DATCOM analysis capability of the fin, a mathematical method was developed to approximate the WAF by a combination of finite numbers of plane segmented fins. Next, the validity of the proposed method is verified by comparison and analysis with wind tunnel test data. The proposed method can be effectively used for the preliminary design phase of the vehicle.
Abstract: In evaluating the system performance, such as vehicle stability, controllability, guidance accuracy, etc., the analysis of aerodynamic characteristics of the vehicle is a priority. In vehicle preliminary design it is necessary to quickly and economically estimate the aerodynamic characteristics of a wide variety of configuration designs. Since the ...
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Research Article
Research on the Mechanism of Drive Force Attenuation in the Robotic Arms of the Da Vinci Surgical System at High Altitudes in Mongolia
Issue:
Volume 11, Issue 2, December 2025
Pages:
29-35
Received:
8 October 2025
Accepted:
17 October 2025
Published:
31 October 2025
DOI:
10.11648/j.ajae.20251102.12
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Abstract: Research Background: Mongolia's high-altitude regions have an average elevation exceeding 1,500 meters, with some areas reaching over 3,000 meters. The unique geographical conditions (hypoxia, low temperatures, strong winds, etc.) may significantly impact the performance of medical robotic systems. As a core device in minimally invasive surgery, the stability of the da Vinci Surgical System's robotic arm driving force is critical to surgical safety and precision. However, systematic research on driving force attenuation in robotic arms under high-altitude conditions remains scarce. This study reviews existing literature and designs virtual experiments to investigate the influence mechanisms of Mongolia's high-altitude environment on the driving force of the da Vinci robotic arm, providing a theoretical basis for optimizing surgical robots in such regions. Research Methods: A multidimensional analytical approach was adopted: Literature Review; Integration of global empirical studies on the effects of altitude on electromechanical systems, focusing on motor efficiency, hydraulic stability, and material deformation. Simulated Environment Design; A controlled climate chamber was used to replicate Mongolia’s high-altitude conditions (2,500–3,500 m, O₂ concentration 15%–18%, temperature −10°C to 5°C), experimental Design for Comparing Robotic Arm Driving Force Output in Standard vs Simulated High-Altitude Environments. Data Modeling; A predictive model for driving force attenuation was developed based on fluid dynamics and motor thermodynamics, alongside potential mitigation strategies. Research Findings: Significant Driving Force Attenuation: Elevated altitudes in Mongolia are associated with diminished peak driving force, while temperatures below −5°C further increase hydraulic oil viscosity, leading to greater response latency. Key Factors: The primary contributing factors include decreased motor heat dissipation efficiency (with an 8% reduction in thermal rise rate per 1,000 m altitude gain) and pressure-induced lubrication deterioration. Nonlinear Relationship: Driving force attenuation exhibits an exponential correlation with altitude, yet the influence of subzero temperatures becomes predominant beyond 2,500 m. Conclusions: Mongolia’s high-altitude environment markedly impairs the da Vinci robotic arm’s driving force due to compounded factors: thermal management failure, hydraulic inefficiency, and material rigidity changes. Design optimizations are recommended, including low-temperature lubricants, enhanced motor cooling, and adaptive control algorithms. Future studies should validate these interventions through field tests to ensure surgical robotic reliability in high-altitude settings. Experimental results will address challenges in deploying the da Vinci system in such regions.
Abstract: Research Background: Mongolia's high-altitude regions have an average elevation exceeding 1,500 meters, with some areas reaching over 3,000 meters. The unique geographical conditions (hypoxia, low temperatures, strong winds, etc.) may significantly impact the performance of medical robotic systems. As a core device in minimally invasive surgery, th...
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Research Article
Mathematical Modelling and Simulation of a Two-Stage Nozzle Flapper Electro-Hydraulic Servo Valve for Aircraft Landing Gear Operation
Isaac Itekulana Mwesigwa*
,
Benjamin William Ndimila,
Bakari Momba Ramadhan
Issue:
Volume 11, Issue 2, December 2025
Pages:
36-45
Received:
1 October 2025
Accepted:
13 October 2025
Published:
7 November 2025
DOI:
10.11648/j.ajae.20251102.13
Downloads:
Views:
Abstract: Electro-hydraulic servo valves (EHSVs) are extensively used in aerospace actuation systems due to their capability to provide precise and rapid control of hydraulic flow. However, accurate mathematical modeling is essential to capture their complex nonlinear dynamics for purposes of simulation, analysis, and control system design. This paper presents a comprehensive mathematical model of a two-stage nozzle flapper EHSV applied to aircraft landing gear operations. The servo valve is divided into five key subsystems: the servo amplifier, voltage-current converter, torque motor, nozzle flapper mechanism, and spool valve integrated with a feedback sensor. Transfer functions are derived for each subsystem and subsequently combined to form an overall system model. The model’s accuracy is validated through simulations conducted in MATLAB/Simulink, enabling detailed performance analysis under various input conditions. Simulation results are used to evaluate system stability, transient response, and overall accuracy. The findings reveal a rapid settling time of 0.85 s, negligible overshoot, and a fine spool displacement of 1.43 × 10-4 m (0.143 mm), demonstrating the model’s capability to achieve stable and precise hydraulic control. These findings highlight the significant potential of the proposed mathematical model to enhance the dynamic performance of aircraft landing gear systems by providing more accurate, stable, and responsive control of hydraulic actuation.
Abstract: Electro-hydraulic servo valves (EHSVs) are extensively used in aerospace actuation systems due to their capability to provide precise and rapid control of hydraulic flow. However, accurate mathematical modeling is essential to capture their complex nonlinear dynamics for purposes of simulation, analysis, and control system design. This paper presen...
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